The present invention relates to a carburetor for an internal combustion engine of a hand-held working tool, especially a diaphragm carburetor comprising a housing and having arranged therein a suction channel with a venturi section. Within the suction channel a throttle is pivotably supported. A control chamber connected with a main fuel channel and an idle channel to the suction channel. A bypass is provided via which, for starting the internal combustion engine, an additional amount of fuel/air mixture is introduced into the suction channel downstream of the throttle.
A diaphragm carburetor for an internal combustion engine is known having a carburetor housing comprising a suction channel with a venturi section and a pivotable throttle arranged in the suction channel. A fuel-filled control chamber is connected via a main fuel channel and an idle channel to the suction channel. In a further housing part connected to the carburetor housing an auxiliary channel is arranged through which during starting of the engine an additional amount of fuel/air mixture is introducible into the suction channel downstream of the throttle. In this embodiment the air supply channel and the fuel supply channel are guided within a mixing channel. At the end of the mixing channel a valve is arranged that opens or closes the access to a further channel which extends to the downstream side of the throttle within the suction channel.
The known arrangement is complicated in its construction and requires additional space external to the actual carburetor housing. Furthermore, a secure sealing at the end of the mixing channel is difficult to achieve so that for safety reasons two independently acting shut-off devices are provided which are arranged in series in the flow direction.
It is therefore an object of the present invention to improve a carburetor of the aforementioned kind such that the auxiliary channel is arranged within the carburetor housing and is inexpensive to manufacture and reliable in its function.